Left-hander Alam was facing spinner Xavier Doherty during the 18th over of Pakistan's innings with Smith positioned at slip.

The Aussie fielder noticed the batsman preparing to play a premeditated sweep shot and just after Doherty released the ball, Smith ran to leg slip where Alam swept the ball and his Australian counterpart took a simple catch, News.com.au reported.

Both on-field umpires conferred before Alam was adjudged out for a fourth-ball duck with the team's total on 3-80 but the batsman remained on the boundary line to seek clarification from a match official before finally walking off, hitting the boundary rope with his bat in frustration as he left the field.

Had the catch taken place before this series, chances are it would have been given not out as the original rules stated that any significant movement by any fielder after the ball comes into play, and before the ball reaches the striker, is unfair.

However, a recent amendment, which is yet to be fully enshrined in cricket law books but is in the 'Match Officials Almanac' for 2014-15, has a different interpretation of the issue.

The updated law states that a fielder is entitled to move before the ball reaches the batsman as long as it's in response to the shot the batsman is shaping to play.

Australia won the match in incredible circumstances, with Glenn Maxwell bowling a double-wicket maiden in the final over to seal a miraculous one-run win and a 3-0 series sweep.